Explanation of a computerand#39;s clock speed. View The Full Article Computers use an internal clock to synchronize all of their calculations. The clock insures that the various circuits inside a computer work together at the same time. The speed of a clock is measured by how many ticks per second the clock makes. This unit of measurement is called a hertz Hz. One hertz equals one tick per second. The clock speed of computers is usually measured in megahertz MHz or gigahertz GHz. One megahertz equals one million ticks per second, and one gigahertz equals one billion ticks per second. Clock speed can be used as a rough measurement of how fast a computer is. A 1.4GHz computer will be faster than a 1GHz computer with the same processor and the same amount of memory. However, clock speed cannot be used to compare computers with different types of processors or computers with different amounts of memory.